(a) Field of the Invention
The present invention relates to a vehicle remote control key system and a signal processing method thereof.
(b) Description of the Related Art
In general, automotive remove control key systems are used to lock and unlock the vehicle doors with a remote control key or used to support an automotive remote control function such as remote start. In the existing automotive remote control key systems, when a user operates the remote control keys, the keys send out a radio frequency (RF) signal of 433 MHz and vehicles within the range that the RF (radio frequency) signal reaches change from a sleep mode to a wake-up mode with a substantially low current to determine whether the received RF signal is an available signal.
FIG. 1 schematically illustrates an exemplary structure of an RF frame from an existing remote control key. Referring to FIG. 1, when an RF receiver of a vehicle receives an RF signal, the ECU (Electronic Control Unit) that controls the vehicle does not wake up, and the RF module wakes up for a short period of time and determines availability of the identification (ID) by checking the received RF frame. When the ID is not an available signal, the RF receiver goes back into the sleep mode with a low current to reduce a dark current. When ID is an available signal, the RF receiver is configured to detect the operation function (Function) and perform the corresponding instruction.
However, since the existing remote control keys are required to have a lifespan of at least two or more years with substantially small batteries, they are limited in output of RF signals. In other words, since the RF signals from remote control keys usually reach about 30 m on the average, when a vehicle is out of the range, an RF signal fails to reach the vehicle and the vehicle may not be remotely operated. Further, when a vehicle is parked in a wide parking lot or many obstacles are present in the vicinity of the vehicle, the transmission distance of RF signals reduces, and the vehicle may not be remotely controlled.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.